By Dr Ananya Mandal, MD
Brain and spinal cord tumors arise as a result of abnormal cells growing in an uncontrolled manner. These tumors may be benign, in which case they rarely spread to other parts of the body, or they may be malignant and highly likely to invade other tissues. Although benign brain tumors do not spread, they can grow large enough to compress other brain areas and cause servere problems such as disability or even death. It is therefore important when diagnosing a brain tumor to ascertain how likely it is to spread and whether or not it can be removed.
Brain and spinal cord tumors are different in adults and children. The tumors often form in different locations and from different cell types. In addition, treatment approaches and patient outlook can differ somewhat. Childhood cancers are often linked to changes in the genetic material that occur before birth and are not strongly associated with lifestyle factors. Childhood cancers also tend to be more responsive to chemotherapy than adult cancers.
Brain tumors may arise from any type of tissues present in the brain and spinal cord. Some tumors also arise from more than one type of cell. Tumors may be treated differently and have different outcomes depending on the area of the central nervous system they have grown in. Compared with adults, brain tumors in children are more likely to originate in the lower part of the brain including the cerebellum and the brain stem.
The types of tumors commonly seen in children include:
Glioma is the term used to describe any tumor that originates in the glial cells meaning many tumors are considered gliomas. Examples of gliomas include glioblastoma, anaplastic astrocytoma, astrocytoma, oligodendroglioma, ependymoma, brain stem glioma and optic glioma.
Gliomas are the most common type of brain tumors seen in children. Mixed gliomas contain more than one cell type. About 10% to 20% of childhood brain tumors are brain stem gliomas and most of these are a form of astrocytoma.
Astrocytomas are tumors that arise from special glial cells called astrocytes. These tumors have the potential to spread throughout the brain and they can be difficult to resect. Astrocytomas are classified as high grade, intermediate grade, or low grade depending on their histological features.
Primitive neuroectodermal tumors (PNETs)
These tumors originate in the immature cells of the central nervous system called neuroectodermal cells. This type of tumor is seen in 20% of childhood brain tumors. They are more common in younger children. PNETs grow and spread quickly throughout the brain and spinal cord.
These are nerve cell tumors and are the third most common type of cancer in children. These rarely develop in the brain or spinal cord but develop in the cells inside the abdomen or chest.
Lymphomas are cancers that start in cells called lymphocytes. They mostly start in other parts of the body but can develop in the central nervous system, although this is rare.
Brain and spinal cord tumor epidemiology in children
Cancer of the brain and spinal cord is the second most common cancer in children and accounts for around 20% of all childhood cancers. These tumors are more common in boys than girls. About 75% of all children with brain tumors go on to survive for at least 5 years after they are diagnosed.
The exact cause of childhood brain tumors are not known and few risk factors have been identified. However, examples of factors that contribute to the risk for these tumors are exposure to ionizing radiation and some congenital conditions, which include: neurofibromatosis type 1 (von Recklinghausen disease), neurofibromatosis type 2, Tuberous sclerosis, Von Hippel-Lindau disease, Li-Fraumeni syndrome, Gorlin syndrome (basal cell nevus syndrome), Cowden syndrome, Rubinstein-Taybi syndrome, Turcot syndrome and hereditary retinoblastoma.
Diagnosis and treatment
Brain and spinal cord tumors may be suspected based on signs and symptoms such as headache, dizziness, vomiting, movement or balance disorders, vision, speech or hearing problems, seizures, numbness and paralysis. Diagnosis is made using imaging studies such as CT scan, MRI scan, PET scan and angiogram. A tissue biopsy of the tumor is also taken to confirm the diagnosis.
The main treatment options for children diagnosed with brain tumors are surgery, radiotherapy and chemotherapy, which may be administered as single therapies or in various combinations, depending on the features of the cancer.
Reviewed by Sally Robertson, BSc